Process for the preparation of tetrabromobisphenol-A

ABSTRACT

This invention relates to a process for the production of tetrabromobisphenol-A by the bromination of bisphenol-A, which process features the addition of bisphenol-A to a reaction mass containing unreacted Br 2  and 30 to 85 wt. % water and an alcohol solvent, the reaction mass being at a relatively high temperature.

This Application is a continuation-in-part of the following U.S. PatentApplications: (1) U.S. Ser. No. 08/426,998 filed Apr. 24, 1995, nowabandoned, which is a continuation-in-part of U.S. Ser. No. 08/398,837filed Mar. 6, 1995, now abandoned; (2) U.S. Ser. No. 08/550,044 filedOct. 30, 1995, issued as U.S. Pat. No. 5,723,690, which is acontinuation of Ser. No. 08/426,997 filed Apr. 24, 1995, issued as U.S.Pat. No. 5,527,971; and (3) U.S. Ser. No. 08/426,996 filed Apr. 24,1995, now abandoned.

This is the U.S. National Stage Application of PCT/US96/05511 filed Apr.18, 1996.

BACKGROUND OF THE INVENTION

This invention relates to highly efficient processes for the preparationof tetrabromobisphenol-A.

Tetrabromobisphenol-A is one of the most widely used brominated flameretardants in the world. It is used extensively to provide flameretardency for styrenic thermoplastics and for some thermoset resins.

The commercial processes used to produce tetrabromobisphenol-A generallyfall into three categories. The first category includes those processesin which substantial amounts of methyl bromide are co-produced alongwith the tetrabromobisphenol-A. Generally, up to 18-23 kg (40-50 pounds)of methyl bromide can be expected per 45.4 kg (100 pounds) oftetrabromobisphenol-A produced. The methyl bromide co-production is nowconsidered desirable since there is a substantial market for thisbromide as a fumigant and as a pharmaceutical or agricultural chemicalintermediate. In most cases, the processes within this first categoryfeature reacting bisphenol-A and bromine in methanol. The ar-brominationof the bisphenol-A is a substitution reaction which generates one moleof HBr per ar-bromination site. Thus, for the production oftetrabromobisphenol-A, four moles of HBr are generated per mole oftetrabromobisphenol-A produced. The HBr in turn reacts with the methanolsolvent to produce the methyl bromide co-product. After the bisphenol-Aand bromine feeds are finished, the reactor contents are cooked for oneto two hours to complete the reaction. At the end of the reaction, wateris added to the reactor contents to precipitate out the desiredtetrabromobisphenol-A product.

The second category of processes features the production oftetrabromobisphenol-A without the co-production of substantial amountsof methyl bromide and without the use of oxidants to convert the HBr toBr₂. See U.S. Pat. Nos. 4,990,321; 5,008,469; 5,059,726; and 5,138,103.Generally, these processes brominate the bisphenol-A at a lowtemperature, say 0 to 20° C., in the presence of a methanol solvent anda specified amount of water. The water and low temperature attenuate theproduction of methyl bromide by slowing the reaction between methanoland HBr. The amount of water used, however, is not so large as to causethe precipitation of the tetrabromobisphenol-A from the reaction mass.Additional water for that purpose is added at the end of the reaction.One drawback with this type of process is that it uses a fairly longaging or cook period after the reactants have all been fed and itrequires additional process time for the final precipitation oftetrabromobisphenol-A via the last water addition.

In the third category are those processes which feature the brominationof bisphenol-A with bromine in the presence of a solvent and,optionally, an oxidant, e.g., H₂ O₂, Cl₂, etc. See U.S. Pat. Nos.3,929,907; 4,180,684; 5,068,463 and Japanese 77034620 B4 77109/05. Thesolvent is generally a water immiscible halogenated organic compound.Water is used in the reaction mass to provide a two-phase system. As thebisphenol-A is brominated, the tetrabromobisphenot-A is found in thesolvent. The co-produced HBr is present in the water. When used, theoxidant oxidizes the HBr to Br₂, which in turn is then available tobrominate more bisphenol-A and its under-brominated species. Byoxidizing the HBr to Br₂, only about two moles of Br₂ feed are neededper mole of bisphenol-A fed to the reactor. To recover thetetrabromobisphenol-A from the solvent, the solution is cooled untiltetrabromobisphenol-A precipitation occurs. This process type is not apanacea though, as there is the expense of handling, purifying andrecycling the halogenated organic solvent. In addition, the cooling ofthe solution to recover tetrabromobisphenol-A entails additional expenseand process time.

As long as there is a viable market for methyl bromide, the processes ofthe first category have been found to be commercially attractive.However, it is now being proposed, on an international level, that theuse of methyl bromide as a fumigant be prohibited. Since the fumigantmarket is the main market for methyl bromide, a need is apparent fortetrabromobisphenol-A processes which do not co-produce a substantialamount of methyl bromide. This is a difficult task since such processes,to be commercially successful, will be required to economically producetetrabromobisphenol-A without the benefit of the revenue realized fromthe sale of co-produced methyl bromide.

The Invention

The processes of this invention feature the efficient production ofhigh-quality tetrabromobisphenol-A in high yields. The processes can berun in the batch mode or in the continuous mode. When run in the batchmode, process efficiency is enhanced due to relatively short reactortimes as there is no need for the prior art's time-consumingpost-reaction cook or aging periods or the often required post-reactiontetrabromobisphenol-A precipitation step. The use of a continuousprocess for the production of tetrabromobisphenol-A is unique in itselfand is made possible by the short reaction and tetrabromobisphenol-Aprecipitation times which are features of the processes of thisinvention. In the continuous mode, reactor size can be substantiallyreduced without a loss in product output.

In addition to the above reaction efficiencies, the processes of thisinvention are capable of producing very pure tetrabromobisphenol-A inhigh yields in an alcohol-based solvent without the substantialconcomitant production of alkyl bromide. Alkyl bromide yields of 5% oftheory or less are possible. Even further, it is possible to obtain highyields of tetrabromobisphenol-A even though less than stoichiometric Br₂is fed to the reactor.

It has been discovered that the foregoing benefits can be obtained by(1) brominating bisphenol-A in the presence of an alcohol, e.g.,methanol, and a relatively large amount of water while maintaining thereaction mass at a relatively high temperature and, (2) adding thebisphenol-A reactant to the reaction mass while the reaction masscontains from 50 to 20,000 ppm Br₂. As will be discussed later, thefeatures in (1) have heretofore conventionally been considered conduciveto the low-yield production of low-quality tetrabromobisphenol-A and/orthe co-production of methyl bromide.

In accordance with this invention, tetrabromobisphenol-A can be producedby a process which comprises:

a. adding bisphenol-A to a reaction mass containing (i) water and asolvent amount of an alcohol containing up to 4 carbon atoms, the waterbeing present in an amount of from about 30 to about 85 wt %, based onthe weight of the water and alcohol in the reaction mass, and (ii) atleast about 50 ppm but less than about 20,000 ppm unreacted Br₂ ;

b. having a reaction mass temperature which is within the range of fromabout 45 to about 100° C., and

c. producing a precipitate which is at least 95 wt %tetrabromobisphenol-A and in a yield which is at least about 90%, basedon the amount of bisphenol-A fed, while concomitantly producing no morethan about 4.54 kg (10 lbs) of alkyl bromide/45.4 kg (100 lbs) oftetrabromobisphenol-A precipitate produced.

The brominations which occur in the processes of this invention occurwith great rapidity. In fact, it is believed that the rapidity withwhich substantially all of the bisphenol-A is tetrabrominated is a keyto obtaining the highly pure products of this invention. The reactionmasses used by the processes of this invention contain significantamounts of water, thus making it incumbent that the tetrabrominationoccur very quickly. If it should not, the prior art teaches that thepresence of large amounts of water will result in the prematureprecipitation of tribromobisphenol-A which will denigrate the puritysought for a tetrabromobisphenol-A product. The use of the hightemperatures for the processes of this invention promote the rapidtetrabromination. However, such temperatures would normally be thoughtto also promote the facile production of alkyl bromide. Despite suchconcerns, the processes of this invention do not exhibit rampant alkylbromide production. Instead, the processes of this invention exhibitminimum alkyl bromide production, say, from about 4.54 to 0.0454 kg (10to 0.1 lbs) or less of alkyl bromide/45.4 kg (100 lbs) oftetrabromobisphenol-A precipitate produced, such production dependingupon the process parameters. Without the use of an oxidant to convertHBr to Br₂, and with methanol as the solvent, the methyl bromideproduction is typically found to be less than 1.8 kg (4 lbs) andpreferably within the range of from about 1.8 kg (4 lbs) to about 0.454kg (1 lb) or less/45.4 kg (100 lbs) of tetrabromobisphenol-A precipitateproduced. With ethanol as the solvent, the alkyl bromide production canbe less than 0.91 kg (2 lbs) and preferably within the range of fromabout 0.91 kg (2 lbs) to about 0.0454 kg (0.1 lb) or less/45.4 kg (100lbs) of tetrabromobisphenol-A.

The bisphenol-A is preferably added to the reaction mass in a moltenform or as a solute in a solution which comprises an alcohol solvent.Less preferred is the addition of the bisphenol-A as a solid. It is animportant feature that the bisphenol-A be added to the reaction masswith its above-stated concentration of unreacted Br₂. Adding thebisphenol-A in this manner is novel and is believed to contribute to thehighly desired rapid tetrabromination. With the presence of thespecified unreacted Br₂ in the reaction mass, the bisphenol-A, as it isbeing fed, always has available the Br₂ needed for its quicktetrabromination but not so much that degradation of the bisphenol-Astructure is realized. Compare the prior art which adds the Br₂ to areaction mass of bisphenol-A. In this latter case, there is insufficientBr₂ available for tetrabromination until near the end of the Br₂ feed,which feed can take 0.5+ hours to effect. Even then, the prior artteaches the need for a post-curing or aging step to complete thetetrabromination. Such post-curing or aging steps entail raising thetemperature of the reaction mass significantly and holding thetemperature for the prescribed curing or aging period. Due to the longtetrabromination times for these prior art processes, it is not possibleto use much more than about 20 wt %water in the reaction mass, as largeramounts of water will result in significant precipitation ofunder-brominated species, e.g., tribromobisphenol-A. Such precipitationwould occur even before the Br₂ feed is complete.

The maintenance of the specified concentration of unreacted Br₂ in thereaction mass can be effected by either adding the Br₂ to the reactionmass or by the in situ production of Br₂ or by both. However the Br₂ isbrought to the reaction mass, its concentration can be easily adjustedto the desired levels by monitoring the reaction mass for the desiredBr₂ concentration and then adjusting the addition of Br₂ and/orbisphenol-A to the reaction mass. If there is to be in situ productionof Br₃ then that production can be adjusted to compliment theadjustments to the Br₂ and/or bisphenol-A additions. These monitoringand adjusting methods are more fully hereinafter described. It ispreferred that the Br₂ be brought to the reaction mass by simpleaddition. The use of the in situ Br₂ production along with direct Br₂addition is also preferred.

It is preferred that the Br₂ be co-fed with the bisphenol-A to thereaction mass. It is more preferred that the co-fed bisphenol-A be as asolute in a solvent comprising alcohol solvent. In a most preferredform, the solvent will also contain water. By co-feeding, it is meantthat the Br₂ feed period and the bisphenol-A or bisphenol-A solutionfeed period overlap one another to at least some extent. (A feed periodis that period of time over which all of a subject feed is fed to thereactor.) For example, the Br₂ feed can be to an initial alcohol/watercharge followed by the bisphenol-A or bisphenol-A solution feed, withthe Br₂ and later feeds thereafter occurring simultaneously untilfinished. Another example would be that of the same initial Br₂ feedfollowed by a continuous bisphenol-A or bisphenol-A solution feed whichis accompanied by a continued, but intermittently interrupted or staged,Br₂ feed. Yet, another example is that of initiating the Br₂ feed to analcohol and water pre-charged reactor followed by the bisphenol-A orbisphenol-A solution feed so that the two feeds occur simultaneouslyuntil the specified amount of Br₂ has been fed. At that point, thebisphenol-A or bisphenol-A solution feed continues alone until it isfinished. Also, the Br₂ and bisphenol-A or bisphenol-A solution feedscan be, timewise, completely concurrent one with the other. Otherco-feeding schemes are possible, it being required that the scheme mustmore closely approximate the addition of the bisphenol-A to a reactionmass having the before-specified unreacted Br₂ concentrations than itapproximates the addition of Br₂ to a bisphenol-A reaction mass.

Commercially available Br₂ is suitable for use as the Br₂ feed. Shouldthe Br₂ contain undesirable impurities, it can be treated byconventional purification techniques, e.g., distillation, H₂ SO₄treatment, etc., which are well known to those skilled in the art.

The Br₂ can be fed as a liquid or as a gas to the reactor. It ispreferred that the feed be gaseous. Whether the Br₂ is liquid orgaseous, it is preferred that the feed entry point be sub-surface of thereaction mass. This is conveniently accomplished by use of a dip tube ina reaction vessel. If the feed is liquid, above-surface feed mustcontend with possible splattering and inefficient mixing.

Processes of this invention feature the use of water in the reactionmass which is within the range of from about 30 to about 85 wt %, basedupon the total amount of water and alcohol solvent in the reaction mass.Preferably, the amount of water in the reaction mass is within the rangeof from about 30 to about 75 wt % water. Most highly preferred is therange of from about 30 to about 70 wt %. When the alcohol solvent ismethanol, the preferred amount of water is from about 30 wt % to about55 wt %. Should the alcohol solvent be ethanol, then the preferredamount of water is from about 40 wt % to about 65 wt %.

The water content of the reaction mass is an important aspect of thisinvention. As before stated, it is believed, for the processes of thisinvention, that the water content greatly attenuates the formation ofmethyl bromide while, unexpectedly, allowing for a high yield of a highpurity tetrabromobisphenol-A product. It is theorized, though theprocesses of this invention are not to be limited by any theory, thatthe formation of methyl bromide is attenuated because the HBr, which isco-produced by the substitution bromination reaction between thearomatic moieties of bisphenol-A and Br₂, is diluted by the large amountof water in the reaction mass. Further, the HBr reacts with the water toyield H₃ OBr which is very slow to react with the alcohol in thereaction mass. As pointed out previously, the attenuated alkyl bromideformation for the processes of this invention does not generally exceedabout 4.54 kg (10 lbs) of alkyl bromide/45.4 kg (100 lbs) oftetrabromobisphenol-A precipitate produced.

With regard to the high yield of a highly pure tetrabromobisphenol-Aproduct, it is noted that typical products from the processes of thisinvention have a tetrabrombisphenol-A purity of at least 95 wt %, basedon the total weight of the recovered product, and atetrabromobisphenol-A yield of at least 90%, based on the bisphenol-Afed. This yield and purity are believed to be due to the largeconcentration of water in the reaction mass. Without being limited toany particular theory, it is believed that the water enhances thepresence of brominating species in the reaction mass. With thisenhancement, there is a favoring of the rapid bromination of thebisphenol-A all of the way to tetrabromobisphenol-A, all before theintermediate, tribromobisphenol-A, has sufficient opportunity to form asignificant amount of precipitate. It is believed that the enhancementof the brominating species is due to the fact that, as before stated,HBr reacts with water to form the H₃ OBr acid. The H₃ OBr acid does notreact as readily with Br₂ as does HBr. This is important because, if H₃OBr was not formed, a larger quantity of HBr would be available to reactwith Br₂ to form HBr₃. The HBr₃ is not desired as it is a weakbrominating species in the reaction mass and its formation consumes Br₂.With less Br₂ available, there is a slowing of the bromination reaction.This slowing can result in an increase in the precipitation oftribromobisphenol-A.

The water in the reaction mass can be supplied thereto by simply beingfed to the reactor as a direct water feed or it may be supplied as aconstituent of the bisphenol-A/alcohol solvent solution or it may besupplied via a direct water feed and as a constituent of thebisphenol-A/alcohol solvent solution. Supplying the water as part ofsuch a solution is convenient and preferred. If the water is introducedto the reaction mass as a separate feed stream, then it may or may notbe fed essentially contemporaneous with the feed of thebisphenol-A/alcohol solvent solution. Even further, a portion, if notall, of the water can be fed as steam or steam condensate along with agaseous Br₂ feed. The stem could have been used to vaporize the Br₂ toform the gaseous feed. Another example features supplying water as acharge or as part of a charge to the reactor prior to initiating thefeeds and adjusting the amount of water later fed to obtain the desiredwater content in the reaction mass. However the water is supplied to thereaction mass, it is preferred it be such that the proper amount ofwater be present in the reaction mass during substantially all of thebisphenol-A feed.

In those cases where the amount of water used is in the lower end of therange, say 30 to 35 wt %, and the other process parameters have not beenoptimally selected, it may be desirable to add some additional water atthe end of the bisphenol-A feed. The possible advantage to such anaddition is that the additional water may cause further precipitation oftetrabromobisphenol-A from the reaction mass. The further precipitationgoes towards increasing the yield of the process.

The alcohol solvent can be supplied as an individual feed or as asolvent constituent of the bisphenol-A solution feed or as both From apractical standpoint though, the alcohol solvent is best fed as asolution constituent. The amount of alcohol solvent in the reaction massis that amount which will insure, in the presence of the water, that thebisphenol-A and its under-brominated intermediates, i.e., mono-, di- andtri- bromobisphenol-A, are essentially soluble and that the desiredtetrabromobisphenol-A is highly insoluble. Such amounts are referred toherein as a "solvent quantity". Generally, the amount of alcohol solventused, expressed as a weight ratio of alcohol to bisphenol-A fed, iswithin the range of from about 1.3:1 to about 10:1. Preferred formethanol is the range of from about 2 to about 5. For ethanol, thepreferred range is from about 1.5 to about 4. A most preferred range formethanol is from about 2.5 to about 4. If the bisphenol-A is to besupplied as a solution in the alcohol solvent, then the alcohol solventcan be supplied to the reaction mass via the solution feed or as a partof the solution feed and the remainder via a separate alcohol feed. Theamount of alcohol solvent in the solution is, at a minimum, that amountwhich will at least provide a flowable slurry and, preferably, afree-flowing liquid. The practitioner can empirically determine theminimum amount needed for the particular alcohol and feed temperaturechosen.

When choosing the weight ratio of alcohol to bisphenol-A fed, it shouldbe noted that the lower ratios, say 1.3 to 2, can result in a highconcentration of HBr in the reaction mass. Reaction mass concentrationsof HBr much in excess of 35 wt % are generally to be avoided. It isbelieved that HBr concentrations of 35+wt %, especially 40+wt %, cancause degradation of and/or inferior product. So that the practitionercan use the lower alcohol to bisphenol-A weight ratios, it is desirableto attenuate the HBr concentration in the reaction mass by feeding anoxidant to the reaction mass, e.g., H₂ O₂ or Cl₂, to oxidize the HBr toBr₂. In this way, the HBr concentration is attenuated and Br₂ is madeavailable to the reaction mass, this latter effect reducing the amountof Br₂ that needs to be fed to the reactor.

In a most preferred form, the bisphenol-A is fed as a solute in solutionwith an alcohol solvent and water. The most highly preferred mode ofoperation is to supply essentially all of the bisphenol-A, alcoholsolvent and water to the reaction mass via such a solution (Some watercan be introduced to the reaction mass as the result of the formation ofalkyl bromide and in those cases where H₂ O₂ is used to oxidize HBr toBr₂. This water goes towards the total water in the reaction mass.) Sucha preferred mode simplifies insuring the proper reaction masscomposition. Indeed, it is most preferred that the bisphenol-A/alcoholsolvent/water solution mimic the alcohol solvent/water composition ofthe reaction mass. Thus, a preferred solution will contain from about 30to about 85 wt % water, based upon the weight of the alcohol solvent andwater. Other preferred ranges mimic the preferred ranges for thereaction mass.

The alcohol solvent is a C₁ to a C₄ alcohol which, in the prescribedamount, is capable of dissolving the Br₂, bisphenol-A,monobromobisphenol-A, dibromobisphenol-A and tribromobisphenol-A underreaction conditions. The reaction conditions of special import are thereaction mass temperature, the presence of unreacted Br₂ in the reactionmass and the reaction mass water content. Further, the alcohol should besubstantially inert with regard to H₃ OBr and the ar-bromination of thebisphenol-A to tetrabromobisphenol-A. The alcohol also should notcontribute to the production of troublesome amounts of color bodies,ionic bromides and/or hydrolyzable bromides. Hydrolyzable bromidesinclude 1-bromo-2-methoxy-2-(3',5'-dibromo-4'-hydroxyphenyl)propane,1,1-dibromo-2-methoxy-2-(3',5'-dibromo4'-hydroxyphenyl)propane,1,3-dibromo-2-methoxy-2-(3',5'-dibromo-4'-hydroxyphenyl)propane, and1,1,3-tribromo-2-methoxy-2-(3',5'-dibromo4'-hydroxyphenyl)propane. Thealcohol, when taken in combination with the water and reactionconditions of the processes of this invention, can have some smallability to dissolve tetrabromobisphenol-A, but for the sake of reactionyield, the dissolving power should be low, say no more than about 10 wt% and preferably no more than about 5 wt % dissolvedtetrabromobisphenol-A in the liquid phase of the reaction mass, theweight percent being based on the weight of the liquid phase.

Exemplary of the preferred alcohol solvents are methanol, ethanolpropanol, butanol and mixtures of any two or more of the foregoing.Polyhydric alcohols such as ethylene glycol and glycerine and any mix ofthe foregoing are also suitable. Further, any mix of any of the alcoholsof this invention is suggested. Most preferred are methanol, ethanol andpropanol, with methanol and ethanol being the solvents of choice.Methanol and ethanol are relatively inexpensive and are easily recoveredby simple distillation techniques for recycle. Since there is a largewater presence in the processes of this invention, it is not necessaryto recover the alcohol with a low water content, thus reducing thealcohol recovery cost.

When choosing the alcohol to be used, the practitioner should considerthat the alcohol chosen will determine the alkyl bromide produced.Hence, methanol will yield methyl bromide, and ethanol will yield ethylbromide. Even though the amount of alkyl bromide produced by theprocesses of this invention is small, there still may be some preferencefor the alkyl bromide produced and that preference might be addressed bythe alcohol chosen.

The reaction mass is essentially a two-phase system, a liquid phase anda solid phase. The former will comprise the reactants, by-product HBr,the alcohol solvent and the water, while the latter will comprise thetetrabromobisphenol-A precipitate. The reaction mass is absent of anyneed for a second liquid phase, such as that which could be provided bya water immiscible organic compound, see U.S. Pat. No. 3,929,907. Thevolume of the liquid phase is generally defined by the amount of alcoholsolvent and water present, the other constituents only making a minorcontribution. The liquid phase volume should be consistent withproviding a stirrable and manageable reaction mass but not so large thatthe volume burdens the process with a need for an overly large reactorand a materials handling problem.

The feed streams are preferably at a temperature which promotesefficient obtainment of the desired reaction mass temperature. Asuitable liquid Br₂ feed temperature is from about 10° C. to just belowthe boiling point of Br₂. If the Br₂ is to be fed as a gas, then the Br₂stream temperature should be that which is conducive to such a feed. Forexample, such a feed temperature may be within the range of from about60 to about 100° C. The bisphenol-A/alcohol solvent solution and/or theindividual feed temperatures should be that which do not detrimentallycool or heat the reaction mass and which allow for the feeds to be madein the liquid state.

The Br₂ and bisphenol-A/alcohol solvent solution and/or separate feedsall contribute to the formation of the reaction mass in the reactor. Aportion of the Br₂ fed to the reactor and/or produced in situ will beconsumed in the bromination reaction. The non-consumed Br₂ preferablyprovides, until it in turn is consumed, for the before-described excessof unreacted Br₂ in the liquid phase.

As a statement of general principle, the presence of the unreacted Br₂in the reaction mass is for the purpose of keeping the Br₂ content inthe reaction mass ahead of the bisphenol-A feed, thus assuring aperbromination condition without unwanted side effects. The presence ofunreacted Br₂ in the liquid phase is extant as bisphenol-A is being fed.It is preferred that the unreacted Br₂ presence be coextensive with thebisphenol-A feed. It is permissible, however, for the unreacted Br2content to stray out of the before-specified ranges for brief periods oftime depending on the level of under-brominated species that can betolerated in the tetrabromobisphenol-A reaction product and/or upon theextent of precipitation of the under-brominated species which isrealized. In fact, if the period of time is very brief and favorablereaction parameters are chosen, the formation of these under-brominatedprecipitates may not occur to any appreciable extent at all. Thepractitioner will have to observe the process and determine by empiricalmethods the sensitivity of the chosen reaction conditions to the briefstraying of unreacted Br₂ content from the specified ranges. Thus, forthe purposes of this invention the "presence of unreacted Br₂ " canencompass brief periods of time in which the unreacted Br₂ content isnot within specification, but which does not result in the formation ofunder-brominated species to an extent that results in an unacceptabletetrabromobisphenol-A product, say one containing less that about 95 wt% tetrabromobisphenol-A.

Quantifying the preferred amount of unreacted Br₂ in the reaction massliquid phase is best handled by a trial and error technique. A trialprocess is first defined by choosing an unreacted Br₂ level and theother process parameters. The produced tetrabromobisphenol-A productfrom the process is analyzed for its tri- and tetrabromobisphenol-Acontent. If the tribromobisphenol-A level is too high another trialprocess is constructed with a higher unreacted Br₂ level or withdifferent process parameters, say raising the reaction mass temperatureor increasing the residence time. The procedure is repeated until thedesired product is obtained. Caution should be taken when adjusting theprocess parameters to insure that the production of unwantedby-products, e.g., tribromophenol, does not become a problem. Once thedesired product has been obtained, the unreacted Br₂ content used isthen measured.

Measuring the unreacted Br₂ content can be performed by the use ofcolorimetric techniques. One technique comprises first forming an acidic(HBr) water and methanol solution. From this solution, severalequivolume samples are drawn. To each sample is added a different andmeasured amount of Br₂. The colors of these sample solutions are thencompared colorimetrically with the color of the reaction mass liquidphase used in the test process. A color match indicates that the Br₂content in the liquid phase of the reaction mass is equal to that in thesample. Colorimetric determination for unreacted Br₂ is suitable ascolor correlates nicely with unreacted Br₂ content. Low concentrationsgive a pale yellow color, intermediate concentrations give a strongyellow color, high concentrations give an orange color, and the highestconcentrations give a dark red color. For the wide range of processconditions disclosed herein, unreacted Br₂ concentrations in excess of50 ppm, but less than about 20,000 ppm, are to be considered.Preferably, the unreacted Br₂ content will be within the range of fromabout 50 to about 15,000 ppm, and most preferably within the range offrom about 2,000 to 6,000 ppm. The ppm values are based upon the weightof the reaction mass liquid phase (liquid portion).

Once the process parameters have been chosen, the maintenance of theunreacted Br₂ concentration in the reaction mass can be accomplished bymeasuring, during the bisphenol-A feed, the Br₂ concentration, e.g., bythe above-described colorimetric technique, then adjusting the Br₂ feed,the bisphenol-A feed or both to obtain the desired Br₂ concentration asagain determined by the colorimetric technique. Since there will betetrabromobisphenol-A precipitate in the reaction mass, colorimetricmonitoring may require that a small stream be taken from the reactor andfiltered to remove the solids before being submitted to a colorimetrictechnique. If removal and filtration is difficult, the reaction masscolor may be read by the use of reflectance techniques which measure theintensity of the light reflected off of the reaction mass. Also, colorcomparisons can be made by use of a portable Hunter Mini-Scan/EXcolorimeter and by comparing the Hunter "a" values of the samples andthe reaction mass. The "a" values appear to correlate well with theexcess Br₂ content The Mini-Scan/EX colorimeter operates by producing aflash of white light onto a sample. The reflected light is dispersed bya holographic grating onto a diode-array detector. Percent reflectancedata is obtained every 10 nm from 400 to 680 nm. This data is used tocalculate the L, a, b, and YI values. In all of the colorimetric cases,the color of the liquid phase of the reaction mass is the determinativefactor.

It is to be understood that techniques other than colorimetrictechniques may be used in monitoring to obtain the desired unreacted Br₂level in the reaction mass. Though the particular technique used is notcritical to the processes of this invention, the use of the colorimetrictechnique is highly preferred.

It is also to be understood that the method used to obtain the desiredunreacted Br₂ level can be by a method other than the adjustment of thebefore-mentioned feeds. For example, when an oxidant is used to convertBr to Br2, the amount of Br₂ generated can be regulated by controllingthe amount of oxidant fed to the reaction mass. The amount of unreactedBr₂ contributed to the reaction mass by oxidation of HBr can besubstantial considering that four moles of HBr are generated for eachmole of tetrabromobisphenol-A produced. Thus, when additional Br₂ isneeded, the practitioner can use the oxidation of HBr to generate atleast a part of the Br₂ needed to obtain the desired unreacted Br₂level.

With the use of an oxidant to oxidize the HBr to Br₂, the processes ofthis invention can obtain good results by feeding only about two molesor slightly more of Br₂ to the reactor for every one mole of bisphenol-Afed. (When speaking of the amount of Br₂ fed per mole of bisphenol-A,the context is the relationship between the overall total amounts ofthese two feeds and is not meant to describe the relationship at any onetime in the reaction mass.) The other two moles of Br₂ that are neededcan be provided by the full oxidation of the co-generated HBr. If thereis less than full HBr oxidation, then the total amount of Br₂ fed to thereactor will be that amount, in sum with the Br₂ formed by oxidation,which will provide at least stoichiometric quantities of Br₂ and,preferably, quantities which are in slight excess of stoichiometric, sayfrom about 0.1% to about 3% percent of stoichiometric. StoichiometricBr₂ for the ar-tetrabromination of bisphenol-A is four moles of Br₂ permole of bisphenol-A. As can be appreciated, if the oxidation of HBr isnot part of process, then the Br₂ feed would be at least stoichiometric(four moles of Br₂ per mole of bisphenol-A fed), with the slight excessbeing preferred, e.g., up to about 4.1-4.25 moles of Br₂ per mole ofbisphenol-A fed.

For batch processes, the excess Br₂ present after completion of theprocess can be removed by treating the reaction mass with a reducingagent, such as sodium sulfite or hydrazine, or by slowly feeding excessbisphenol-A until essentially all bromine has reacted.

If an oxidant is used to convert HBr to Br₂, the oxidant can be anywhich is capable of oxidizing HBr to Br₂ in the reaction mass and underthe process conditions of this invention, all without deleterious affecton the production of tetrabromobisphenol-A in high purity and in highyields. Preferred oxidants are those in liquid or gas form whichfacilitates their feed to the reactor. Preferred oxidants are chlorineand hydrogen peroxide.

When Cl₂ is the oxidant, it can be fed to the reaction mass as a gas oras a liquid. The gaseous feed is preferred. To mitigate against theformation of chlorinated bisphenol-A, it is preferred that the Cl₂ befed after initiation of the Br₂ feed. After the initial Br₂ feed, Cl₂can be fed contemporaneously with the Br₂ feed. Even with this feedsequence, some bromochlorobisphenol-A compounds will be formed.Fortunately, these bromochloro species are present in very minoramounts, say from about 50 to about 500 ppm, based on the total weightof the precipitate. The most predominate bromochloro specie will, inmost cases, be chlorotribromobisphenol-A.

When the oxidant is H₂ O₂, safety makes it preferable that it be fed tothe reaction mass in an aqueous solution containing no more than about90 wt % H₂ O₂. Preferred are aqueous solutions containing from about 30to about 80 wt % H₂ O₂. A most preferred solution is one containing fromabout 50 to about 70 wt % H₂ O₂.

The H₂ O₂ can be fed to the reaction mass at any time. For batchoperation, it is preferred that the H₂ O₂ be fed after most of the Br₂,say above about 50%, has been fed. For continuous operation, the H₂ O₂feed would most preferably occur contemporaneously with at least most ofthe Br₂ feed. Most preferably, the H₂ O₂ feed would start afterinitiating the Br₂ feed.

The oxidants can be fed to the reaction mass separately or in somecases, along with the Br₂ feed. It is preferred that the Cl₂ be fedthrough the same feed conduit as is the Br₂ and may be fed while Br₂ isbeing fed. In distinction, the H₂ O₂ is preferably fed as a separatefeed stream

The amount of oxidant fed is preferably that amount needed to oxidizethat amount of HBr which is needed to yield the desired amount of Br₂.Both H₂ O₂ and Cl₂ are capable of oxidizing HBr on a one mole to twomole basis. Thus, relating the oxidant to the bisphenol-A feed anddepending upon the amount of HBr that is set for oxidation, a typicalmole ratio of H₂ O₂ or Cl₂ to bisphenol-A will be within the range offrom about 1:1 to about 2:1. A more preferred mole ratio is from about1.5:1 to about 1.9:1. The higher oxidant ratios are preferred when H₂ O₂is the oxidant, while the mid-range ratios, say 1.5-1.8:1, are preferredwhen Cl₂ is the oxidant. The reason that the lower oxidant ratios arepreferred for Cl₂ is that there is a balance between the amount of HBroxidized and the amount of chlorobromo species which can be tolerated.If there is no need to keep the chlorobromo species to some minimumamount, then more Cl₂ is permissible. Adjustments to the above rangesare necessary if the oxidant chosen does not oxidize the HBr on a one totwo basis. In these cases, the ranges are adjusted in proportion to thevariance in the one to two relationship.

Another important consideration in practicing the processes of thisinvention is the reaction mass temperature. It is desirable to use arelatively high temperature so that the bromination of the bisphenol-Ato tetrabromobisphenol-A will be sufficiently fast to attenuate theformation of tribromobisphenol-A precipitate. However, there is apractical limit as to how high the temperature can be. For example, thepractitioner would not want to use temperatures which would cause theproduction of unacceptable levels of unwanted by-products or thedegradation of the tetrabromobisphenol-A product.

It is unusual to operate a tetrabromobisphenol-A process at relativelyhigh temperatures during the addition of a reactant, that is, for theinstant case, bisphenol-A. This is especially so when the production ofalkyl bromide is to be minimized. It is conventional to expect that hightemperatures will yield large amounts of methyl bromide. Also, the useof high temperatures is not conventional when the precipitation of thetetrabromobisphenol-A is to occur under reaction conditions soon afterit is formed-such precipitation being a feature of the processes of thisinvention. It would be expected that high temperatures would frustratesuch precipitation by increasing the solubility of thetetrabromobisphenol-A in the solvent solution and require a finalcooling of or addition of water to the reaction mass to effect thedesired precipitation. The processes of this invention are not soaffected, nor is there required a cooling step to obtaintetrabromobisphenol-A precipitation. In addition, the use of the highertemperatures of this invention reduce process costs as the processes canuse cooling tower water to cool the reactor instead of having to userefrigeration which is required by the low temperature processes.

Preferred reaction mass temperatures are within the range of from about30 to about 100° C. More highly preferred temperatures are within therange of from about 50 to about 100° C. The most highly preferredtemperatures are within the range of from about 50 to about 75° C.Temperatures of 30 to 50° C. are best when the liquid phase of thereaction mass is large.

The bromination of bisphenol-A is an exothermic reaction as is theoxidation of HBr with an oxidant. To control the reaction masstemperature, it may become necessary to remove heat from the reactionmass. Heat removal can be effected by running the reaction at refluxwith a condenser facilitating the heat removal. If it is desired tooperate at a temperature below the atmospheric boiling point of thereaction mixture, the reaction can be run under sub-atmosphericpressure.

Generally, the basic concepts of the processes of this invention are notappreciably affected by the process pressure. Thus, the process can berun under sub-atmospheric, atmospheric or super-atmospheric pressure.

At process initiation, it is desirable to charge the reactor with aliquid pre-reaction charge which will become a part of the reaction massupon the commencement of the feed. The liquid charge will provide astirrable reaction mass and act as a heat sink to moderate temperaturechanges in the reaction mass. The liquid charge is preferably comprisedof water and the alcohol solvent fed in the solution. It is preferredthat the liquid charge be acidic, e.g., containing from 1 to 30 wt %acid such as a hydrohalogenic acid, e.g., HBr, HCl, or the like. Theacid seems to promote good color in the initial tetrabromobisphenol-Aproduced. Further, it is preferred that the solvent be saturated withdissolved tetrabromobisphenol-A. It is also preferred that the reactorbe charged with seed particles of tetrabromobisphenol-A. The saturationof the solvent and the presence of the seed particles both act toenhance the precipitation of the tetrabromobisphenol-A produced duringthe bromination period. It is most practical to use a heel from apreviously run process of this invention as the liquid charge. Thetetrabromobisphenol-A seed particles can be brought over from theprevious run or can be added separately. If a heel is not available, itis also possible to use a separate pre-reaction charge of water, acid,and alcohol solvent. The only caveat to this scheme is that there mustbe apportionment of the various feeds so that there will still becompliance with the various parameters which define the processes ofthis invention.

It is beneficial to insure that the reaction mass liquid portion isacidic in nature. This can be easily accomplished by insuring a presenceof HBr in the reaction mass during at least a portion of the reactionperiod, and preferably during all of the reaction period. If the HBrproduced from the aromatic bromination is not oxidized to Br₂, then thatHBr can act to accomplish the acidification. Generally speaking, thereaction mass liquid portion should contain from about 1 wt % to about30 wt % HBr, based on the total weight of liquid portion of the reactionmass. Most preferred is the range of 7 wt % to about 20 wt % HBr. It ismost preferred to have an acidified reaction mass at process initiation.This can be accomplished by using the before-mentioned "heel" oracid/alcohol solvent/water pre-charge. Having an initial acidiccondition is more important when the process is run in the batch mode asthe product produced without such a condition becomes part of the totalproduct produced. In the continuous mode, the product produced withoutthe initial acid condition will be produced during the first hours ofprocess start-up. This sub-standard product can then be recovered anddiscarded. As the continuous process runs further, the acid build-up inthe reaction mass reaches steady state and becomes sufficient. Productproduced under these acid conditions can then be recovered withoutcontamination from the initially produced product. In the case of usingan oxidant to convert the HBr to Br₂, care must be taken to not oxidizeall of the HBr in the reaction mass and to thus leave sufficient HBrpresent to give the acid condition and acquire the color benefit. WhileHBr is the preferred acid, other mineral acids may be used, HCl, HF, HIor mixtures thereof

When the process of this invention is run as a batch process, the Br₂and bisphenol-A feeds are fed to a stirred reactor until they areexhausted. There is no need for a post-feed cook or aging period of anysignificant length as, under the reaction conditions, the bromination ofbisphenol-A to tetrabromobisphenol-A occurs quite rapidly. Also, sincethe water content of the reaction mass is so large and since thetetrabromobisphenol-A is so insoluble in the presence of such an amountof water, there is generally no need for or, at best, only a modicum ofbenefit is obtained by cooling the final reaction mass to obtain furtherprecipitation. The benefit of cooling resides mainly in reducing thevapor pressure of solvated gaseous bromides, e.g., methyl bromide, inthe reaction mass prior to the liquid-solids separation. There alsocould be some slowing of the formation of these bromides. Finally,depending on the separation technique used, cooling the reaction massmay make it easier to handle downstream from the reactor. Thus, if noneof the above are of concern or relative value, then the reaction masscan be simply subjected to liquid-solids separation as soon as thebisphenol-A feed is finished. From a practical standpoint though, sometime will lapse as the reaction mass will need to be transported to theseparation equipment. If, however, cooling is desired, the cooling timewill depend upon how the reaction mass is to be cooled and to whattemperature it is to be cooled. In a laboratory setting, cooling timescan range from about one to about thirty minutes.

After the recovery of the solids from the liquid, the solids arepreferably washed with a solution of water and the particular alcoholused in the reaction. The washing removes essentially all the motherliquor from the solids. The mother liquor contains impurities such astribromophenol HBr, and hydrolyzable impurities. A typical wash can be a30 wt % methanol or ethanol in water solution. The washed solids arethen rewashed with deionized water to remove any remaining watermiscible solvent from the first wash so as to minimize emission problemswhen drying the product.

When run in the continuous mode, the reactor is preferably acontinuously stirred tank reactor. The reaction mass is beingcontinuously formed and a portion thereof is being removed from thereactor during the reaction mass formation. The reactor design should besuch that the average residence time in the reactor is sufficient toinsure the tetrabromination of substantially all of the bisphenol-A. Thefeeds to the reactor and the precipitate removals can be interrupted solong as they are recurrent. The terms "continuous feed" and "continuouswithdrawal" mean being characterized by continued occurrence orrecurrence and are not meant to exclude interrupted feeds orwithdrawals. Generally, such interruptions are of short duration and maybe suitable depending upon the scale and design of the reactor. Forexample, since the tetrabromobisphenol-A precipitate will tend to settlenear the bottom of the reactor, a withdrawal may be made and thenstopped for a period of time to allow for precipitate build-up to occurprior to the next withdrawal. Such a withdrawal is to be consideredcontinuous in the sense that the withdrawal does not await thecompletion of the reactor feeds and is recurrent. Such features are notgenerally thought of as being characteristic of batch processes.

Whether the continuous withdrawal is interrupted or not, the withdrawalresults in a portion of the liquid and a portion of the solids in thereaction mass to be withdrawn together. The solids portion will bepredominately tetrabromobisphenol-A. The solids portion can be filtered,the precipitate washed, etc., as is done for the above-described batchmode case.

When using the continuous mode of operation, it is believed that itwould be beneficial if the reaction mass temperature be kept fairly highas compared to the temperatures preferred for the batch mode. Preferredbatch mode temperatures are from about 50 to about 65° C. For thecontinuous mode, the preferred temperatures are within the range of fromabout 55 to about 95° C., and most preferably within the range of fromabout 65 to about 95° C. Very good results are predicted withtemperatures of from about 65 to about 75° C. By using the highertemperatures, it was found that higher purity product could be obtained.

The benefit of high temperatures on product purity is understood in viewof studies which support the correlation between product purity and therelative rates of bromination and precipitation of thetribromobisphenol-A intermediate. Raising the temperature benefits boththe reaction rate and the solubility of the tribromobisphenol-A in thereaction mass liquid phase and thus, promotes the obtainment of a pureproduct. An increase in Br₂ or an increase in the tribromobisphenol-Aconcentration in the liquid phase by reducing the liquid phase alcoholand water content can also increase the bromination rate of thetribromobisphenol-A, but, both present problems of their own A high Br₂concentration can cause the formation of undesirable by-products, whiledecreasing the liquid phase alcohol and water content will increase theHBr content of the reaction mass. The result is a reduction in thetetrabromobisphenol-A product purity.

It is acted that in the continuous mode of operation, the preferredreactor residence time should be within the range of from about 10 toabout 150 minutes when using a continuously stirred tank reactor and theprocess conditions which are preferred for that operating mode. Morepreferred residence times are within the range of from about 15 to about90 minutes. Most preferred is from about 20 to 70 minutes. Reactorresidence time, as used herein, is the volume of the reactor contentsdivided by the flow rate at which slurry is removed from the reactor.

The tetrabromobisphenol-A product produced by the processes of thisinvention contains at least about 95 wt % tetrabromobisphenol-A andpreferably at least about 97.5 wt % tetrabromobisphenol-A and, mostpreferably, at least about 98.5 wt %. The best products are those havingabove about 99 wt % tetrabromobisphenol-A. All wt % are based on totalweight of the precipitate. The product quality is excellent, having anAPHA color less than about 50 (80 grams of tetrabromobisphenol-A in 100ml of acetone). Preferably, the APHA color range is between 25 and 50.Hydrolyzable bromides are also kept low, generally below about 60 ppm.The process yields are impressive, with yields being at least about 90%and preferably within the range of from about 95 to about 99%.

As can be appreciated from the foregoing, the bisphenol-A feed, thewater content of the solvent, the reaction temperature and the Br₂content in the reaction mass during the bisphenol-A feed all contributeto obtaining the desired tetrabromobisphenol-A product in an efficientmanner. The selection of particular values for each of these processparameters to obtain the results desired will depend on eachpractitioner's needs and upon the equipment available. One practitionermay emphasize one benefit of using a process of this invention overother possible benefits. Thus, that practitioner may select differentprocess parameter values than those selected by another practitioner whodesires to highlight other benefit(s).

A preferred set of process parameters is: alcohol/BPA wt ratio of 1.3-5;Br₂ content in the reaction mass--about 2,000 to 6,000 ppm; processtemperature--50-75° C.; residence time (continuous mode)--about 30 to 70minutes; and weight percent H₂ O--about 35 to 60 wt %, based on weightof H₂ O and alcohol solvent. Most preferred is the set of: alcohol/BPAwt ratio of 2-4; Br₂ content in the reaction mass--3,000 to 6,000;process temperature--about 60-75° C.; residence time (continuous mode)40-50 minutes; and weight percent H₂ O--about 40-55 wt %, based uponweight of H₂ O and alcohol solvent.

The use of oxidation to generate Br₂ is particularly attractive in thosecases where the oxidation is more economical than the cost of providingfor an equivalent amount of Br₂ in the feed to the reactor. The economicadvantage is usually extant in those cases where the costs of feedingfour moles of Br₂ minus the value of recovered HBr is greater than thecosts of feeding two moles of Br₂ plus the oxidation of the HBr.

Though preferably designed to minimize the production of methyl bromide,the processes of this invention are sufficiently adaptable to bemodified to produce moderate amounts of alkyl bromide. Alkyl bromideproduction can be increased by cooking or aging the reaction mass postthe tetrabromobisphenol-A formation to give sufficient time for thealcohol-HBr reaction to occur. For the continuous mode of operation, theresidence time would be increased beyond that which is needed to producethe tetrabromobisphenol-A precipitate.

While the foregoing descriptions of the oxidation of HBr generally speakof the HBr being oxidized in the reactor or reaction mass, it is withinthe scope of the processes of this invention to also remove co-producedHBr from the reactor and oxidize it outside of the reactor and to thensend the so produced Br₂ back to the reactor.

It is also within the scope of the processes of this invention toprovide HBr to the reactor from a source other than the reaction in thereactor. This non-indigenous HBr can be oxidized along with theco-generated HBr to yield Br₂. The Br₂ produced from the non-indigenousHBr can then count against the total Br₂ needs of the process and theappropriate adjustment in the Br₂ feed can be made. The non-indigenousHBr feed can also be adjusted to insure an acidic reaction mediumdespite the oxidation of HBr.

EXAMPLES

The following Examples illustrate principles of processes of thisinvention.

In each of the Examples a pre-reaction charge or "mother liquor" wasused which essentially contained water, methanol, HBr and much smalleramounts of impurities. Generally, the mother liquor contained about 30wt % water and about 55 wt % methanol and about 8-20 wt % HBr.

The mother liquor used in Examples I-II came from TBBPA made asdescribed in U.S. Pat. No. 4,628,124 by Mitchell and McKinnie.

In Examples III-VI, different mother liquors were used. The motherliquors used in Examples III and IV came from a series of previousexperiments in which tetrabromobisphenol-A was produced by the reactionof bisphenol-A and bromine in a reaction mass containing methanol andwater. These previous experiments were either not of this invention(water amounts, temperature, etc., were outside of defined parameters)or gave conflicting and inconclusive results. The mother liquor from thefirst experiment not of this invention was used in the second experimentand so on. The mother liquor from the last experiment provided themother liquor for Example III.

In all Examples, unless otherwise indicated, the % associated with aproduct is to be taken as gas chromatography (GC) area percent. GCanalyses were performed on a 5 Meter×0.53 mm HP-1 megabore capillarycolumn of 2.65 micron film thickness using split injection. The columnwas operated from 100° C. to 300° C. with heating at 10° C. per minute.A flame ionization detector was used.

Examples I-III illustrate the production of a high-qualitytetrabromobisphenol-A product with the concomitant oxidation ofco-produced HBr to Br₂, which Br₂ was used to contribute to thebromination of bisphenol-A to the desired tetrabrominated product.

Example I

A one liter round bottom flask was equipped with a mechanical stirrer,condenser, thermometer, addition funnel, heating mantle, and fitted witha 0.3175 cm (1/8 inch) O.D. dip tube for feeding bromine and a 0.3175 cm(1/8 inch) feed tube, which terminated in the vapor space, for feedingbisphenol-A solution. The flask was charged with 200 ml of mother liquorcontaining 9.5 wt % HBr and about 5.0 grams of tetrabromobisphenol-A.The added tetrabromobisphenol-A acted to saturate the mother liquor andto provide seed particles to aid in the precipitation oftetrabromobisphenol-A to be produced.

A solution comprised of 100 grams of bisphenol-A, 300 ml of methanol (2%water) and 200 ml of water was prepared. 143 grams (46 ml) of Br₂ wasplaced in a vaporizer consisting of a 250 ml heated flask that had anitrogen inlet and a gas outlet connected to the 0.3175 cm (1/8 inch)dip tube in the reactor. The pre-reaction charge of mother liquor andtetrabromobisphenol-A was brought to a temperature of about 55° C. Br₂feed was started by purging nitrogen (about 200 to 500 ml/min) throughthe vaporizer and heating the liquid bromine. As soon as the pre-reactorcharge took on a yellow color, the solution feed was begun by use of aperistaltic pump. The Br₂ feed was kept stoichiometrically ahead of thebisphenol-A feed by variation of the pumping rate, and as a result, thereaction mass had a yellow color. The feeds continued for 1 hour and 15minutes when the Br₂ feed was finished. The solution feed was continueduntil the liquid phase of the reaction mass was colorless. The additionfunnel was charged with 100 grams of aqueous H₂ O₂ (30 wt %) anddropwise addition was initiated with the continued feed of thebisphenol-A solution. The aqueous feed and the solution feeds wereperiodically adjusted to keep the liquid portion of the reaction mass ayellow color. The reaction mass temperature was kept at 60-63° C. duringthe aqueous H₂ O₂ feed. After all of the H₂ O₂ was added, the reactionmass was yellow. Continued addition of the bisphenol-A solution wouldturn the mass light yellow, but the deeper yellow would return uponcessation of the solution feed. During this period, the reactiontemperature was 58-62° C. Finally, 20 minutes after cessation of theaqueous hydrogen peroxide feed, the bisphenol-A solution was added untilthe reaction mass was colorless. The reaction mass was held at atemperature of 60-65° C. for about one-half hour and then cooled toabout 55° C. The reaction mass precipitate was separated from the motherliquor by filtration and then washed with 125 ml of 20 wt % methanol inwater solution. A second wash with deionized water was performed. Thewashed precipitate was dried and analyzed. GC analysis showed 0.64%tribromobisphenol-A and 99.3% tetrabromobisphenol-A. The mother liquorwas found to contain 3.7 wt % HBr.

Example II

A one liter round bottom flask was equipped as above except there was noaddition funnel and in the line from the bromine vaporizer to theconnection to the dip tube was a tee for addition of chorine gas. Motherliquor (150 grams) and 3 grams of solid tetrabromobisphenol-A were addedto the flask and heated to a temperature of about 55° C. A Br₂ vapor andN₂ feed was started to the flask via the dip tube followed by the feedof a solution prepared from 80.0 grams bisphenol-A, 400 ml of methanol(2 wt % water) and 200 ml of water. The total amount of Br₂ to be fedwas 141 grams. After a few minutes, a slight gaseous Cl₂ feed wasstarted. The liquid portion of the reaction mass was kept yellow byadjusting the bisphenol-A and Cl₂ feeds. All of the Br₂ had been fed inabout 1.5 hours. The Cl₂ feed was increased to above 90 ml/min and wasadjusted continuously to keep the liquid portion of the reaction massyellow as bisphenol-A was fed at about 6 ml/min. All of the Cl₂ andbisphenol-A was fed after 2 hours. After 2 minutes from the cessation ofthese feeds, 2 drops of hydrazine (66 wt %) was added to destroy excessBr₂. The hydrazine rendered the liquid portion of the reaction masscolorless. The reaction mass was cooled to 20° C. The precipitate wascollected and washed with 125 ml of 30 wt % methanol in water. A secondwashing with deionized water yielded a wet cake which was then ovendried at 120-130° C. to yield 189.8 grams of product. GC analysis showed0.79% tribromobisphenol-A, 0.01% chlorotribromobisphenol-A, 0.04%o,p-tetrabromobisphenol-A and 99.1% tetrabromobisphenol-A.

Example III

A one liter flask was equipped as in Example IV with bromine being fedas in Example IV, except that there was placed in the nitrogen feed atee for the addition of chlorine gas. The reactor was charged with 150ml of a mother liquor obtained from a reaction mixture similar toExample II. This was heated to about 55° C. and addition of brominevapor initiated. When the reaction mass took on a yellow color, theaddition of a solution prepared from 90.0 grams of bisphenol-A, 450 mlof methanol, and 180 ml of water was started. After five minutes, theaddition of 150-200 ml per min of chlorine gas was begun. The reactionmixture was kept at about 55° C. and was kept a yellow color byadjusting the solution flow rate. After an additional 20 minutes,chlorine flow was increased to about 250 ml per minute and after anadditional 30 minutes, chlorine flow was increases to 300 ml per minute.20 minutes later, all bromine had been added. 47 ml of bromine had beenadded. Chlorine flow rate was increased to maintain the reaction mass asa yellow color. Eight minutes later, all solution had been fed, at whichtime chlorine addition was discontinued. After seven minutes, about 2 mlof saturated sodium sulfite solution was added to destroy bromine. Thereaction mixture was then cooled to 30° C. The solids were separatedfrom the mother liquor by filtration and then washed on the filter with125 ml of 30% methanol and then 125 ml of deionized water. The solid wasoven dried leaving 209.2 grams that by GC analysis was 1.25%tribromobisphenol-A, 0.013% chlorotribromobisphenol-A, and 98.7%tetrabromobisphenol-A. The solid had an acetone color (80 grams in 100ml of acetone) of 20 APHA, 6 ppm ionic bromide, and 16 ppm hydrolyzablebromide. Analysis of the mother liquor showed it to contain 0.09 wt %tribromophenol 0.21 wt % tetrabromobisphenol-A, about 3 ppmtribromobisphenol-A, and about 0.04 wt % other phenolic impurities.

The following Examples illustrate principles of processes of thisinvention, which processes do not feature the oxidation of HBr toprovide for reactant Br₂.

Example IV

A one liter round bottom flask was equipped with a mechanical stirrer,condenser, thermometer, heating mantle, and fitted with a 0.3175 cm (1/8inch) O.D. dip tube for feeding bromine and a 0.3175 cm (1/8 inch) feedtube, which termination in the vapor space, for feeding bisphenol-Asolution. The flask was charged with 150 ml of a mother liquor and 5.0grams of tetrabromobisphenol-A. The added tetrabromobisphenol-A acted tosaturate the mother liquor and to provide seed particles to aid in theprecipitation of tetrabromobisphenol-A to be produced.

A solution comprised of 59.93 grams of bisphenol-A, 360 ml of methanol(2% water) and 123 ml of water was prepared. 168.2 grams of Br₂ wasplaced in a vaporizer consisting of a 250 ml heated flask that had anitrogen inlet and a gas outlet connected to the 0.3175 cm (1/8 inch)dip tube in the reactor. The pre-reaction charge of mother liquor and 5grams of tetrabromobisphenol-A was brought to a temperature of about 67°C. Br₂ feed was started by purging nitrogen (about 200 to 500 ml/min)through the vaporizer and heating the liquid bromine. As soon as thepre-reactor charge took on a yellow color, the solution feed was begunby use of a peristaltic pump. The Br₂ feed was kept stoichiometricallyahead of the bisphenol-A feed by variation of the pumping rate, and as aresult, the reaction mass had an orange color. The feeds continued for 1hour and 38 minutes when the Br₂ feed was finished. About 20 ml of thesolution feed was left which was not added. After the solution feed wasfinished, the reaction mass was held for an additional 20 minutes atabout 67-69° C. The reaction mass was colorless. The solids werecollected by filtration and washed with 30% methanol in water then waterand dried at a temperature of about 125° C. Gas chromatography (GC)showed the solids were comprised of 0.22% tribromobisphenol-A and 99.8%tetrabromobisphenol-A.

Example V

Essentially the same procedure was followed as in Example IV, exceptwhere noted. Mother liquor (150 ml), obtained from the filtrate ofExample IV, and 5 grams of tetrabromobisphenol-A were charged to theflask at the beginning. The feed solution was made from 80.0 gramsbisphenol-A, 400 ml of methanol and 210 ml water. 225.4 grams of Br₂were used. The solution was fed at about 6 ml/min and the Br₂ was fedwith a N₂ sweep at 200-500 ml/min. The reaction mass was kept at atemperature of 55-60° C. and was kept a dark yellow color by slightvariation of rates of the feeds. The solution and Br₂ feeds werecompleted essentially at the same time. The flask from which thesolution was fed was as with 10 ml of methanol. The wash liquid was thenfed to the reaction flask. The resultant reaction mass had a lightyellow color after the wash liquid feed and five minutes from thestoppage of the solution and Br₂ feeds. Three drops of 63% hydrazinewere added to the reaction flask to deactivate any remaining Br₂. Thereaction mass was stirred for 1.5 hours without the addition of heatthen the solids collected by filtration and washed with an aqueous 40%methanol solution then water. GC showed the solids to contain 0.02%tribromophenol, 0.84% tribromobisphenol-A and 99% tetrabromobisphenol-A.

Example VI

The same procedure was followed as in Example V, except where noted. Themother liquor (150 ml) came from the filtrate of Example IV. Three gramsof tetrabromobisphenol-A were used with the mother liquor. The solutioncontained 80.16 grams of bisphenol-A, 380 ml of methanol and 300 ml ofwater. 225.1 grams of Br₂ were fed. The mother liquor was heated to 55°C. and then the Br₂ and solution feeds were started. The reaction masswas kept yellow by adjusting the Br₂ feed. The two feeds were finishedin about two hours, the reactor temperature being maintained at 55-60°C. throughout the additions. The solution container was rinsed withabout 10 ml of methanol which then was added to the reaction flask. Thereaction mass was then light yellow. About 7 minutes after the feedswere finished (and the methanol rinse liquid was added), 2 drops ofhydrazine were added to the reaction mass. The reaction mass becamecolorless. The reaction mass was left to cool to room temperature andsettle. A sample of the liquid portion of the reaction mass was taken.Analysis by dilution with water and extraction with methylene chloridefollowed by GC analysis using tetradecane as internal standard showedthat the liquid contained 0.036 wt % tribromophenol, 0.040 wt %tetrabromobisphenol-A, about 0.001 wt % tribromobisphenol-A and about0.027 wt % other impurities, which corresponds to a yield loss of about0.5% of theory.

The washed and dried solids recovered from the reaction mass where shownby GC to contain 1.8% of tribromobisphenol-A and 98.2%tetrabromobisphenol-A.

Example VII

A 2 liter round bottom flask was equipped as in Example IV, except theliquid bromine and a nitrogen stream (30-100 ml/min) were fed to a 1.83meter (6 ft) length of 0.635 cm (1/4 inch) Teflon tubing held in boilingwater to vaporize the bromine. This vaporized bromine was then fed tothe 0.3175 cm (1/8 inch) dip tube. A pre-reaction charge was formed byadding 18 ml of Br₂ over 20 minutes to a 2 L reactor which alreadycontained 20 grams of bisphenol-A and 100 ml of methanol. The reactorcontents were heated to reflux during the Br₂ addition and so maintainedfor 5 minutes after the Br₂ feed was completed. 100 ml of water was thenadded to the reactor. The resultant reactor contents comprised thepre-reaction charge.

Subsequent to the formation of the pre-reaction charge, there was added,over one hour, a co-feed comprised of 94 ml of liquid Br₂ and about 1400ml of a bisphenol-A solution prepared from 130 grams of bisphenol-A, 650ml of methanol and 950 ml of water. During the co-feed the reaction masswas a yellow to orange color and was kept at a temperature of 57-60° C.Additional bisphenol-A solution (about 3 ml) was added after the co-feeduntil the reaction mass turned light yellow. The reaction mass wascooled to about 35° C. and filtered to yield a precipitate which waswashed with a 30% aqueous methanol solution. Then the precipitate waswashed with 250 ml of deionized water. After oven drying, theprecipitate was weighed and was found to weigh 295 grams. GC analysisfound 0.03% tribromophenol; 1.16% tribromobisphenol-A, 0.064%o,p-tetrabromobisphenol-A and 98.7% tetrabromobisphenol-A.

Example VIII

A 500 ml flask was equipped as in Example VII, including the bromineaddition method of Example VII. There was included also a 0.635 cm (1/4inch) Teflon dip tube attached to a pump for removing reaction mixture.This pump, capable of pumping 167 ml per min, was attached to a timersuch that it pumped reaction mixture from the flask only about 3 secondsof every 45 seconds.

The reactor was charged with 400 ml of reaction mixture from a previousrun and heated to 67° C. The addition of bromine vapor was then begun.As soon as the mixture turned yellow, the addition of a solution ofbisphenol-A (1000 g. bisphenol-A in 5200 ml of MeOH [3.74% water] and1670 ml of water) was begun at a rate of about 12 ml/min. Fractions ofthe reaction mixture were collected in Erlenmeyer flasks that contained1/2 ml of 63% hydrazine. The bromine feed rate was controlled to keepthe reaction mixture yellow and the reaction temperature was maintainedat 69-71° C. The reactor level was maintained at about 400 ml by smalladjustments of the rate at which the reaction mixture was pumped fromthe flask. After fractions were collected, they were separated from themother liquors by filtration and the solids washed with 30% MeOH andthen deionized water on the filter. Table I gives the results. SampleNo. 5 was collected without added hydrazine. Analysis of it's motherliquor showed 360 ppm bromine. GC analyses of two of the mother liquorson a 5 meter HP-1 megabore capillary column using tetradecane asinternal standard, are shown in Table II.

                  TABLE I                                                         ______________________________________                                               Time Sample  Volume of                                                 Sample Collected, minutes                                                                         Sample MI % Br, BPA                                                                             % TBBPA                                 ______________________________________                                        1       0 to 75     1000      1.0     98.9                                    2       75 to 152   1000      1.0     98.9                                    3      152 to 306   2000      1.2     98.8                                    4      306 to 382   1000      1.2     98.7                                    5      382 to 527   1900      1.2     98.7                                    ______________________________________                                         Br.sub.3 BPA  tribromobisphenolA                                              TBBPA  tetrabromobisphenolA                                              

                  TABLE II                                                        ______________________________________                                        ANALYSIS OF MOTHER LIQUOR                                                     GC Retention Time,     No. 3 Sample                                                                             No. 5 Sample                                min.        Compound   mother liq.                                                                              mother liq.                                 ______________________________________                                        5.17        TBP        0.040 wt % 0.042 wt %                                  9.76        Unknown    0.016 wt % 0.017 wt %                                  9.97        Hydrolyzable                                                                             0.025 wt % 0.027 wt %                                              impurity                                                          12.61       DBBPA      0.031 wt % 0.001 wt %                                  14.99       Br.sub.3 BPA                                                                             0.20 wt %  0.025 wt %                                  17.15       ThBPA      0.53 wt %  0.42 wt %                                   Total, wt %            0.84 wt %  0.53 wt %                                   % Yield Loss           2.6        1.6                                         ______________________________________                                         TBP  tribromophenol                                                           DBBPA  dibromobisphenolA                                                      Br.sub.3 BPA  tribromobishenolA                                               TBBPA  tetrabromobisphenolA                                              

Example IX

A one liter round bottom flask was equipped as in Example IV, excepttemperature control was provided by a circulating bath on the jacket ofthe flask. The bromine was vaporized as in Example VII except heat wasadded by electric heating tape controlled with a laboratory variac.Additionally, a 35% H₂ O₂ aqueous solution was added using a peristalticpump through an 0.3175 cm (1/8 inch) O.D. tube terminating in thereactor vapor space. There was also a 0.9525 cm (3/8 inch) diameterglass dip tube added to the reactor which was attached to a sealedreceiving flask by a jacketed, heated tube sloped so that gravityenhances the flow. A vacuum is periodically pulled on the receivingflask by a peristaltic pump, capable of pumping 167 ml per min, attachedto a timer so that it pumped only about 7 seconds of every 147 seconds.This modification from Example VIII was necessary to consistentlywithdraw the approximately 60% by weight solids slurry from the reactor.

A prereaction charge of 400 ml existed in the reactor from previousexperimental work. The mixture comprised TBBPA particles, ethanol,water, and HBr in approximately the same proportions as would begenerated by the feed streams. The mixture was heated to 40° C. beforethe addition of bromine was begun at 1.15 ml/min. As soon as the mixtureturned yellow, the addition of a solution of bisphenol-A (relative ratioof 100 g. bisphenol-A in 75 grams absolute ethanol) was begun at a rateof 3.75 ml/min. The 35% H₂ O₂ solution feed was then begun at 1.30ml/min. All the necessary water was provided by the H₂ O₂ solution,either as water or a product of the HBr reoxidation reaction. Thetemperature of the reaction mixture rose rapidly to 72° C. upon startingthe feeds of bisphenol-A and H₂ O₂, and fell to 66° C. as the runprogressed. The slight changes in the H₂ O₂ or bromine feed rates weremade to keep the reaction mixture yellow. Fractions of the reactionmixture were collected in the receiving flasks whose size matches theliquid volume in the reactor (400 ml). When full, these receiving flasksare removed from the system, and the excess bromine is quenched byadding 35% hydrazine aqueous solution dropwise.

The collected fractions were separated from the mother liquors byfiltration and the solids washed with 30% EtOH and then deionized wateron the filter. The resulting solids were oven dried, dissolved inacetone, and analyzed by GC to determine the TBBPA purity.

Fraction 3, represent the third residence time in the reactor, had aproduct purity of 99.6% TBBPA, 0.4% Br₃ BPA, average particle size of137 microns. The mother liquor contained 0.54% TBP and 0.35% TBBPA.

Fraction 4 had a product purity of 99.3% TBBPA, 0.7% Br₃ BPA, averageparticle size of 152 micron. The mother liquor contained 0.45% TBP and0.31% TBBPA. The reaction mass was found to be 58% solids by weight.

Fraction 5 had a product purity of 99.2% TBBPA, 0.8% Br₃ PPA, averageparticle size of 156 micron. The mother liquor contained 0.43% TBP and0.34% TBBPA.

The increase in the relative amount of TBP in the mother liquor overprevious work is not due to an increase in production rate, but ratherto the small amount of solvent present in this run. The solid samplesdid not show any significant TBP present other than trace amounts.

It is to be understood that the processes of this invention can be runin combination with processes having process parameters not of thisinvention. For example, if the practitioner wished to produce anintermediate amount of methyl bromide, a process similar to the instantprocess can be run but with process parameters which promote theformation of methyl bromide, say for example the process could feature alow water content, e.g., 10 wt %. This process could be run for a periodof time and then could be interrupted with the imposition of theparameters of this invention so as to diminish methyl bromideproduction. In this way, the practitioner could control the methylbromide production within narrow production limits by combining bothprocesses.

As can be appreciated from the above and when viewed in their broadestaspects, the processes of this invention effect the high yieldproduction of a highly pure tetrabromobisphenol-A product by providing areaction system in which there is directly formed atetrabromobisphenol-A precipitate at such speed that there isinsufficient opportunity for the significant precipitation of theintermediate, tribromobisphenol-A.

As before stated, it is a feature of the processes of this invention,that precipitation of tetrabromobisphenol-A occurs during the feeding ofbisphenol-A to the reactor and that the precipitate so formed containsat least 95 wt % tetrabromobisphenol-A and with a yield of at least 90%based on the bisphenol-A fed. This feature is extant whether the processis batch or continuous. When the process is run in the continuous mode,this feature results in the continuous recovery of highly puretetrabromobisphenol-A from the reaction system. Even further, when theprocess is run in the batch mode, this feature results in obtaining highpurity tetrabromobisphenol-A in the absence of a need for a reactionmass cook time after the last of the reactant feeds has been completed.Indeed, the precipitate can be recovered from the batch reaction massimmediately or as soon as is practical from a materials handlingstandpoint. The processes of this invention can exhibit yields withinthe range of from about 90% to about 99.5%, based upon the bisphenol-Afed to the reaction. Preferred yields are within the range of from about95% to about 99%.

We claim:
 1. A process for the production of tetrabromobisphenol-A,which process comprises:a. feeding bisphenol-A to a reaction mass havinga reaction mass temperature which is within the range of from about 30to about 100° C. and having an acidic liquid phase, which liquid phasecontains (i) water and a solvent quantity of an alcohol having up to 4carbon atoms, the water being present in an amount of from about 30 toabout 85 wt %, based on the weight of the water and alcohol solvent inthe reaction mass, and (ii) at least about 50 ppm but less than about20,000 ppm unreacted Br₂ ; and b. during the feeding in (a), producing aprecipitate which is at least 95 wt % tetrabromobisphenol-A and in ayield which is at least about 90%, based on the amount of bisphenol-Afed.
 2. The process of claim 1 wherein the bisphenol-A is added in themolten form.
 3. The process of claim 1 wherein the bisphenol-A is addedas a solute in a solution containing an alcohol solvent having up to 4carbon atoms.
 4. The process of claim 3 wherein the liquid phase of thereaction mass contains from about 1 wt % to about 30 wt % mineral acid.5. The process of claim 1 wherein the alcohol in the reaction mass ismethanol, ethanol, propanol, ethylene glycol, glycerine or a mix of anytwo or more of the foregoing.
 6. The process of claim 1 wherein thealcohol solvent in the reaction mass is methanol, ethanol or a mixturethereof.
 7. The process of claim 1 wherein the reaction mass water ispresent in an amount of from about 30 to about 70 wt %, based on theweight of the water and alcohol in the reaction mass.
 8. The process ofclaim 1 wherein the reaction mass contains from about 50 to about 15,000ppm unreacted Br₂.
 9. The process of claim 1 wherein the reaction masscontains from about 2,000 to 6,000 ppm unreacted Br₂.
 10. The process ofclaim 1 wherein the reaction mass temperature is within the range offrom about 50 to about 80° C.
 11. The process of claim 1 wherein (i) thealcohol in the reaction mass is selected from methanol, ethanol or amixture thereof; (ii) the reaction mass contains from about 30 to 85 wt% water based on the weight of the water and alcohol in the reactionmass and from about 2,000 to about 6,000 ppm unreacted Br₂ ; (iii) thereaction mass temperature is within the range of from about 50 to about80° C.; and (iv) the liquid phase of the reaction mass contains fromabout 1 wt % to about 30 wt % mineral acid.
 12. The process of claim 1wherein the alcohol is ethanol and the amount of alkyl bromide producedis within the range of from about 0.91 kg (2 lbs) to about 0.0454 kg(0.1 lbs) or less/45.4 kg (100 lbs) of tetrabromobisphenol-A precipitateproduced.
 13. The process of claim 1 wherein Br₂ and bisphenol-A areco-fed to the reaction mass.
 14. The process of claim 13 wherein theunreacted Br₂ concentration in the reaction mass is at least partiallyobtained by monitoring the unreacted Br₂ reaction mass concentration andadjusting, as needed, the co-feed of the Br₂, the bisphenol-A or both toobtain the desired unreacted Br₂ concentration.
 15. The process of claim13 wherein the bisphenol-A is added as a solute in a solution containingan alcohol solvent having up to 4 carbon atoms.
 16. The process of claim15 wherein the solvent is methanol, ethanol, propanol, butanol or a mixof any two or more of the foregoing.
 17. The process of claim 13 whereinthe liquid phase of the reaction mass contains from about 1 wt % toabout 30 wt % mineral acid.
 18. The process of claim 13 wherein thereaction mass water is present in an amount of from about 30 to about 70wt %, based on the weight of the water and alcohol in the reaction mass.19. The process of claim 13 wherein the reaction mass contains fromabout 50 to about 15,000 ppm unreacted Br₂.
 20. The process of claim 13wherein the reaction mass contains from about 2,000 to about 6,000 pmunreacted Br₂.
 21. The process of claim 13 wherein the reaction masstemperature is within the range of from about 50 to about 80° C.
 22. Theprocess of claim 13 wherein (i) the alcohol in the reaction mass isselected from methanol, ethanol and a mix thereof; (ii) the reactionmass contains from about 30 to about 85 wt % water, based upon theweight of water and alcohol in the reaction mass; (iii) the reactionmass contains from about 2,000 to about 6,000 ppm unreacted Br₂ ; (iv)the reaction mass temperature is within the range of from about 50 toabout 80° C.; and (v) the liquid phase of the reaction mass containsfrom about 1 wt % to about 30 wt % mineral acid.
 23. The process ofclaim 13 wherein the alcohol is ethanol and wherein the amount of ethylbromide produced is no more than about 4.54 kg (10 lbs) per 45.4 kg (100lbs) of tetrabromobisphenol-A precipitate produced.
 24. A process forthe production of tetrabromobisphenol-A, which process comprises:a.feeding bisphenol-A to a reaction mass having a reaction masstemperature which is within the range of from about 30 to about 100° C.and having an acidic liquid phase, which liquid phase contains (i) waterand a solvent quantity of an alcohol having up to 4 carbon atoms, thewater being present in an amount of from about 30 to about 85 wt %,based on the weight of the water and alcohol solvent in the reactionmass, and (ii) at least about 50 ppm but less than about 20,000 ppmunreacted Br₂ ; b. providing at least a portion of the unreacted Br₂ in(a) by the oxidation of HBr to Br₂ ; and c. during the feeding in (a),producing precipitate which is at least 95 wt % tetrabromobisphenol-Aand in a yield of at least about 90 wt %, based on the amount ofbisphenol-A fed.
 25. The process of claim 24 wherein the HBr is oxidizedwith H₂ O₂ or Cl₂.
 26. The process of claim 24 wherein the HBr isoxidized with H₂ O₂.
 27. The process of claim 24 wherein the reactionmass additionally contains from about 1 to about 30 wt % hydrohalogenicacid.
 28. The process of claim 27 wherein the hydrohalogenic acid isHBr.
 29. The process of claim 24 wherein the bisphenol-A is added in themolten form.
 30. The process of claim 24 wherein the bisphenol-A isadded as a solute in a solution containing an alcohol having up to 4carbon atoms.
 31. The process of claim 30 wherein the alcohol in thebisphenol-A solution is selected from methanol, ethanol, propanol,butane, ethylene glycol glycerine or a mix of any two or more of theforegoing.
 32. The process of claim 24 wherein the alcohol in thereaction mass is methanol, ethanol or a mix thereof.
 33. The process ofclaim 24 wherein the reaction mass water is present in an amount of fromabout 30 to about 70 wt % water, based on the weight of water andalcohol in the reaction mass.
 34. The process of claim 24 wherein thereaction mass contains from about 50 to about 15,000 ppm unreacted Br₂.35. The process of claim 24 wherein the reaction mass contains fromabout 2,000 to about 6,000 pm unreacted Br₂.
 36. The process of claim 24wherein the reaction mass temperature is within the range of from about50 to about 80° C.
 37. The process of claim 24 wherein (i) the alcoholin the reaction mass is selected from methanol, ethanol and a mixturethereof, (ii) the reaction mass contains from about 30 to 85 wt % water,based on the weight of the water and alcohol in the reaction mass, andfrom about 2,000 to about 6,000 ppm unreacted Br₂, and (iii) thereaction mass temperature is within the range of from about 50 to about80° C.
 38. The process of claim 24 wherein the HBr is oxidized with H₂O₂, the bisphenol-A is added as a solute in a solution containing analcohol having up to 4 carbon atoms, and wherein the reaction massadditionally contains from about 1 to about 30 wt % hydrohalogenic acid.39. The process of claim 24 wherein HBr is oxidized in the reactionmass.
 40. The process of claim 24 wherein HBr is oxidized external ofthe reaction mass.
 41. The process of claim 24 wherein the alcohol isethanol and wherein the amount of ethyl bromide produced is no more thanabout 4.54 kg (10 lbs) per 45.4 kg (100 lbs) of tetrabromobisphenol-Aprecipitate produced.
 42. A process for the production oftetrabromobisphenol-A, which process comprises:a. continuously addingbisphenol-A to a reaction mass having a reaction mass temperature whichis within the range of from about 30 to about 100° C. and having anacidic liquid phase which contains (i) water and a solvent quantity ofan alcohol containing up to 4 carbon atoms, the water being present inan amount of from about 30 to 85 wt %, based on the weight of the waterand alcohol in the reaction mass and (ii) at least about 50 ppm but lessthan about 20,000 ppm unreacted Br₂ ; b. during the addition in (a),producing a precipitate which is at least 95 wt % tetrabromobisphenol-Aand in a yield which is at least about 90%, based on the amount ofbisphenol-A fed; and c. continuously removing at least a portion of theprecipitate from the reaction mass.
 43. The process of claim 42 whereinthe alcohol in the reaction mass is methanol, ethanol, propanol,ethylene glycol, glycerine and a mix of any two or more of theforegoing.
 44. The process of claim 42 wherein the bisphenol-A is addedas a solute in a solution containing an alcohol having up to 4 carbonatoms.
 45. The process of claim 42 wherein at least a portion of theunreacted Br₂ is obtained from the oxidation of HBr to Br₂.
 46. Theprocess of claim 45 wherein the reaction mass additionally contains fromabout 1 to about 30 wt % hydrohalogenic acid.
 47. The process of claim46 wherein the hydrohalogenic acid is HBr.
 48. The process of claim 45wherein the HBr is oxidized with H₂ O₂, the bisphenol-A is added as asolute in a solution containing alcohol having up to 4 carbon atoms andwherein the reaction mass additionally contains from about 1 to about 30wt % hydrohalogenic acid.
 49. The process of claim 48 wherein HBr isoxidized in the reaction mass.